P3D Re: Stereo Nomenclature 2000

[Bruce Springsteen <bsspringsteen@xxxxxxxxx>]

I gave the impression this morning that no one, not even Abram, had really
engaged my idea that the traditional definition of orthostereoscopy is in
need of clarifying reform.  This was not true - Abram did a very nice
three-part response on December 20, just before P3D (and apparently I)
slipped into a brief coma.  Let me recapitulate:

First, picking up on the general theme of stereo nomenclature, he
distinguished between glossaries that *describe* usage as it is found, and
those that *prescribe* usage based on authoritative opinion formed by
committees.  He noted that unless there is some institution of world-wide
authority with some power to enforce usage among practitioners, such
prescriptive efforts may become quickly ridiculous.  He mentioned that, if
pressed, he could come up with his own list of stereo words that need
clarification or standardization - "parallax" being one.  Then he offered
a very interesting summary of efforts in recent decades to standardize the
German and English terminology of stereo, involving DIN, ISU and an
assortment of modern stereo scholars, his own illustrious self among them.
 Of particular relevance to my concern was the following by Dalgoutte:
>orthostereoscopic image -  one having 'right-looking solidity',
>in which the space-image resembles the original closely but is not
>truly 'tautomorphic' (as in gigantism and lilliputism).

>tautomorphic image - one which has the 'same form and scale and
>position' as the original object, where stereomagnification = 1.

Which, if I am reading it right, seems to grant my wish to restrict
"ortho" to duplicating the shapes of space, by preservation of perspective
(as in the equivalent one-eyed 2D viewing rule), without reference to any
apparent size or distance relative to an "average" human interpupillary. 
The term "tautomorphic" here seems to stand in for what I called
"anthropostereo", or "normal" orthostereo where an attempt is made to
match the human scale.

Abram then addressed my seeming need to devise a "Philosophy of
Stereoscopy" (his flattering term) wherein pure principles based on
measurable truths are sharply defined, and the vague nature of perception
and the relativity of merely human frames of reference are kept in a
separate terminology where they won't cause so much trouble.  He gently
admonished me that the whole pursuit of stereoscopy is about humans and
their fuzzy, illusionary perceptions - which will never conform to
geometry alone - and that precise prediction of perceptions is futile
(don't resist).  It was a very interesting and excellent response, as
usual, but that last was a bit of a "straw man", rather than my actual
view. 

Fortunately, I don't really seek a rarified discipline where only the pure
archetypes of geometry are deemed relevant.  No such thing.  I know and
revel in the quirky nature of perception, but I want "orthostereo" to be
defined as a way of controlling the measurable aspects of this art,
regardless of the individual observer who will come into it later, so as
to understand the real things that *trigger* those perceptions out in the
viewing space before the brain is involved.  In this way we can begin to
distinguish what is really before us, and what we "see" or think we "see",
and how they relate to one another.  Is the "stretch" I see really there
in the viewing circumstances, or is it in my imagination?  Why does the
pair of prints I mounted with one infinity separation look different to me
from the one I mounted with another spacing - I can't quite figure out
what's up by eye.....  and so on.  Abram says that "orthostereo" is not a
set of conditions, but just a general philosophical statement (about
seeing the size and shape of things as in "reality") without prescribing
how that is to be accomplished.  That's exactly what I want to change,
because I think it confuses people and fails to do what a good practical
definition should do - tell you how to get there.

Thanks Abram, and I hope I have not totally missed your point - or failed
to make my own.
Bruce (the Gadfly) Springsteen





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